UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Agency revenues		$ 3,435	$ 3,541	$ 7,991	$ 8,221
Merchant revenues		1,313	1,050	2,875	2,286
Advertising and other revenues		292	258	861	807
Total revenues		5,040	4,849	11,727	11,314
Operating expenses:
Performance marketing		1,291	1,314	3,513	3,562
Brand marketing		124	160	462	385
Sales and other expenses		276	243	739	612
Personnel, including stock-based compensation of $79, $70, $232 and $216, respectively		566	537	1,686	1,558
General and administrative		225	183	596	505
Information technology		71	58	206	177
Depreciation and amortization		117	107	352	317
Total operating expenses		2,670	2,602	7,554	7,116
Operating income		2,370	2,247	4,173	4,198
Other income (expense):
Interest income		44	48	113	141
Interest expense		(70)	(68)	(204)	(203)
Net unrealized (losses) gains on marketable equity securities		(49)	31	419	107
Foreign currency transactions and other		68	(18)	37	(40)
Total other (expense) income		(7)	(7)	365	5
Earnings before income taxes		2,363	2,240	4,538	4,203
Income tax expense		413	473	844	851
Net income	[1]	$ 1,950	$ 1,767	$ 3,694	$ 3,352
Net income applicable to common stockholders per basic common share (in dollars per share)		$ 46.01	$ 37.39	$ 84.84	$ 70.00
Weighted-average number of basic common shares outstanding (in shares)		42,389	47,268	43,540	47,887
Net income applicable to common stockholders per diluted common share (in dollars per share)		$ 45.54	$ 37.02	$ 84.06	$ 69.07
Weighted-average number of diluted common shares outstanding (in shares)		42,831	47,751	43,947	48,530

[1] The Company reclassified from accumulated other comprehensive income a net gain of $10 million ($11 million before tax) and a net loss of $1 million ($1 million before tax) for the nine months ended September 30, 2019 and 2018, respectively, from sales of investments in debt securities.
In addition, for both the three and nine months ended September 30, 2019, the Company reclassified from accumulated other comprehensive income a tax charge of $21 million related to the maturity in August 2019 of the Company's investment of $500 million in Trip.com Group (formerly known as Ctrip.com International Ltd.) convertible notes (see Note 5).
The reclassified net gain and loss before tax are included in "Foreign currency transactions and other" and the reclassified tax charges are included in "Income tax expense" in the Unaudited Consolidated Statements of Operations.